How do you turn a powder into solid?

Answer 1

powder IS solid.

However, if you wanna make it into a larger chunk again, there are several ways. One is to melt it, then cool it, and you will have solid. However, you could dissolve it into other solutions, and then evaporate that solution, to form larger chunks, etc. =)

Answer 2

To turn a powder into a solid, you can use a process called compaction. This involves applying pressure to the powder, which forces the particles to bond together and form a solid mass. Compaction can be done using methods such as compression molding or pelletizing, depending on the specific properties of the powder.